Propeller



J. FISCHER May 10, 1949.

PROPELLER Filed 001:. 18 1944 2 Sheets-Sheet 1 J. FISCHER May 10, 1949.

PROPELLER 2 Sheets-Sheet 2 Filed Oct. 18,1944

Patented May 10 1949 UNITED STATES PATENT OFFICE 1 Claim. 1

This invention relates to propellers or airscrews.

An object of this invention is to provide a propeller which is constructed in the form of a double blade, there being a main blade and an auxiliary blade with the latter having the same pitch as the main blade and spaced forwardly therefrom.

Another object of this invention is to provide a propeller h-aving extending from the forward side of each blade thereof an auxiliary blade which is of the same pitch as the main blade and which is narrower than the main blade with the leading edge thereof trailing the leading edge of the main blade.

A further object of this invention is to provide a propeller in which the main and auxiliary blades are mounted on a common hub and are connected together at their trailing edges.

In the drawings:

Figure 1 is a detail front elevation of a propeller constructed according to an embodiment of this invention.

Figure 2 is a detail end elevation of the propeller shown in Figure 1.

Figure 3 is a sectional view taken on the line 3-3 of Figure 1.

Figure 4 is a detail front elevation of a modified form of this invention.

Figure 5 is a detail end elevation of the propeller shown in Figure 4.

Figure 6 is a sectional view taken on the line 66 of Figure 4.

Figure 7 is a detail front elevation of another modification of this invention.

Figure 8 is a detail end elevation of the propeller shown in Figure 7.

Figure 9 is a sectional view taken on the line 9-9 of Figure '7.

Figure 10 is a detail front elevation of another modification of this invention.

Figure 11 is a sectional view taken on the line lll| of Figure 10. Referring to the drawings and first to Figures 1, 2 and 3, the numeral [5 designates generally a hub which is adapted to be secured to a drive shaft for rotation therewith.

The hub l5 has secured thereto a pair of oppositely extending main propeller blades l6 and I1 which are formed with the desired pitch angle and the blades l6 and I! which are of like construction are formed with a leading edge l8, which at the outer portion thereof is curved rearwardly as indicated at [9, and the curve I9 terminates at the trailing edge of the blade Hi.

The propeller also includes a pair of auxiliary blades 2| and 22 which are disposed in forwardly spaced parallel relation to the blades it and M respectively. The auxiliary blades 2| and 22 are of like construction and each includes a leading edge 23, which is positioned rearwardly from the leading edge [8 of the main blade I6. The trailing edge of the auxiliary blad 2! is connected or secured to the leading edge 29 of the main blade [6 by means of inner and outer connecting members 24 and 25 and an intermediate connecting member 26. A pair of openings 2'5 and 28 are formed between the inner connecting member and the intermediate connecting member 26, and between the intermediate connecting member and the outer connecting member 29. The body of the blade 23 is additionally braced or secured to the forward side of the main blade It by means of a plurality of combined spacer and securing pins 29.

Referring now to Figures 4, 5 and 6, there is disclosed a modified form of propeller blade structure which includes a hub 39, having secured thereto a pair of radially arranged main propeller blades 3| and 32. The propeller blades 3| and 32 include a leading edge 33 and a trailing edge 34. A pair of auxiliary blades 35 and 36 are disposed in forwardly ofiset relation with respect to the blades 3| and 32, respectively, and the blades 35 and 36 have their leading edges 31 and 38,respectively, disposed in rearwardly spaced relation with respect to the leading edges 33 of the main blades. The auxiliary blades 35 and 36 are of like construction and each auxiliary blade is connected to the trailing edge of the main blades by means of integral connecting members 39 and 49. The connecting members 39 and 40 are inner and outer connecting members, respectively, thereby providing a relatively long slot or passage 4| at the trailing edges of the main and auxiliary blades. The outer end of each auxiliary blade is additionally braced by means of a substantially triangular block 42 which is positioned between the tips of the main and auxiliary blades, and one side of the block 42 extending upwardly and rearwardly as indicated at 43.

Referring now to Figures 7, 8 and 9 there is disclosed a further modification of this invention embodying a hub 44, having extending radially therefrom a pair of main propeller blades 45 and 46. A pair of auxiliary blades 41 and 48 are disposed in forwardly spaced parallel relation to the forward side of the blades 45 and 46, respectively. The inner portions of the blades 41 and 48 are spaced from the blades 45 and 46 by means of spacer blocks 49 and 50, respectively, and the outer ends of the auxiliary blades are secured to the outer portion of the main blades by means of combined spacer and securing pins 5|. The leading edges 52 of the auxiliary blades are of longitudinally concave configuration, which is opposed to the convex configuration of the leading edges 53 of the main blades. The leading edges 52 are spaced rearwardly from the leading edges of the main blades.

Referring :now. .toijigures and;1 1, '3there-=is disclosed a" further modification of "this invention embodying a hub 54 having a pair of main propeller blades 55 and 56 extending radially therefrom. The blades 55 and 56 are of like construc- 7} tion and each includes a body E'I disposed on the desired pitch angle and including-a-trailing' portion 58, which is disposed on angobtuse angle with respect to the body 51'. A pairofauxiliary blades 59 and 60 are disposed in forwardly' 'spaced parallel relation with respect to the blades 55 and 5- r u a yab e fifen 0v are: oillike construction; andeach; includes; a; body: ;6 boom- .prising the leading. portion; 1 and-=whichzisiinrmed :with. a" concavei-leading-edge 62.

' Anobtusely, disposed :trailing porti na B 3, isgdos- ,posedparallel with :thepbtusely, disposed -,portion :ofthe-main blade; anda ;1; ea1- ;;or trailingzedge -64 of the auxiliary blade isgcoplanariwithjthe convex trailing: .ed egpf the main: blade. The; auxiliary blades 59;; and fiflraresubstantially-ishorter: :in

length thantherlength of :the; main .blades:55 and '56,; and the outer. .end .portions of; the? auxiliary blades: arelfirmly secured. in; spacedxrelation with respect tothe. main blades by :means: of combined spacerzand securing pins55'. With a. propeller. constructed according toy this invention, :the auxiliary"?blade: being'i' 'foi wardly pfz'ithe 1. main :blade, land being: not? only; small in width, but positioned rearwardly of the": leadingedgeoor the main blade,- wil1 not matei ially '40 ,4 affect the operation of the main blade, but will provide an additional pulling force so that the main blade will not slip as greatly in the air stream.

What I claim is:

A propeller comprising a cylindrical hub, oppositely extending main blades overlying the rear end of said hub and extending radially therefrom, an auxiliary blade overlying each of said main 1O iblddies ionith'ei fdrward "sijdezther'of said auxiliary ."'blade overlying 'the forwardend'of said 'hub and extending outwardly therefrom parallel to said main blade, spacers between said auxiliary blade ;-alfld said main blade, the leading edge of said auxiliary blade being disposed rearwardly of the ea'ding edge of said main blade, the trailing .':;edgegoi saidzmain blade extending rearwardly at least as far as the trailing edge of said auxiliary made? JOSEPH FISCHER.

REFERENCES CITED "Elie iollowing ref erences are obreeor d ini'the iile oi'fthis patenti UNITED STATES} PATENTS Number :TNa-me Date 1285;2-12 ;-'Be11 eta1 -:sept;-18; 1883 1 ,344,496 ".Flattur'n June 22," 1920 so 11345355 Wi1lour June 29; 1920 623,868 i'Fis'cher "1Apr. 5, 1927 f; 2,199,823 Kesser'y Ma '7,4940 1 2,344,266 I Reissner lVIar; 14, 1944 I EQREJGN; BA'IENTS Number 1 Country 3379 Great- Britain I 416,799 Great Britain 427,493 Great Britain 

